Book/Report

FZJ-2018-03431

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Bruchmechanische Untersuchungen zum Rißwiderstandsverhalten bei nichtumwandlungsverstärkten Keramiken am Beispiel von Aluminiumoxid

Bär, K. K. O. (Corresponding author)FZJ* ; Kleist, G.FZJ* ; Nickel, H.FZJ*

1991
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/18876

Report No.: Juel-2460

Abstract: The aim of this work is the clearification of R-curve behaviour of non-transforming ceramics, in particular aluminum- oxide exhibiting incrystalline fracture. Investigations of crack growth in controlled bending experiments were performed using -3-Ptf and 4-Pt-bending samples of differing sizes under inert conditions. The fracture experiments were realized using several loading techniques, for example constant and varying displacement rates, load rupture (P = 0) and relaxation tests (v = 0). In addition unloading and reloading experiments were performed to investigate hysteresis curves and residual displacements in accordance with R-curve behaviour.During the crack-growth experiments, the crack extension was measured in situ using a high resolution immersion microscop. With this technique, the fracture processes near the crack tip (crack activity zone) was observed as well. The crack resistance as a function of crack extension (R-curve) was determined using differing calculation methods. All of the methods used resulted in approximately identical R-curves, within the statistical error band. The crack resistance at initiation R$_{o}$was 20 N/m. The crack resistance increased during approximately 3 mm of growth to a maximum of 90 N/m. A decrease in the crack resistance was determined for large a/W (crack length normalized with sample height) values, independant of the calculation methods. The R-curve behaviour was interpreted as due to a functionalresistance behind the observed crack tip, which arises from a volume dilatation in the crack activity zone while the crack proceeds.

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Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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Database coverage:

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